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W E DeCoteau

Publications and source records attributed to W E DeCoteau.

At least 19 recordsLinked to original sources
PubMed2000

A double dissociation between the rat hippocampus and medial caudoputamen in processing two forms of knowledge.

Rats with hippocampus, medial caudoputamen (CPU), lateral CPU, or control lesions were trained on declarative and procedural knowledge variants of a novel rodent sequential learning task. Medial CPU lesions impaired rats' ability to learn the procedure of running through a sequence of open maze arms but did not disrupt their capacity to explicitly generate (i.e.. "declare") maze arm sequences. Hippocampus lesions produced the opposite set of results. Rats with lateral CPU lesions were not impaired on either version of the task. Transfer tests indicated that control rats predominantly used egocentric cues to solve the procedural task and allocentric spatial cues to solve the declarative task. These findings suggest a double dissociation between the medial CPU and hippocampus in processing egocentric-procedural and allocentric-declarative sequential information, respectively.

Animals↗
PubMed1998

Memory for spatial location: role of the hippocampus in mediating spatial pattern separation.

A paradigm based on measuring short-term memory for spatial location information as a function of spatial similarity between distal cues was developed to examine the role of pattern separation in the modulation of short-term memory for spatial information. A delayed-match-to-sample for spatial location task using a dryland version of the Morris water maze was used to assess spatial pattern separation in male Long-Evans rats. In the sample phase, animals were trained to displace an object that covered a baited food well in one of 15 spatial locations along a row of food wells perpendicular to a start box. In the ensuing choice phase, the animal was allowed to choose between two objects identical to the sample phase object. One covered the same baited food well as did the object in the study phase (correct choice), and another foil object (incorrect choice) covered a different unbaited food well along the row of wells. Five spatial separations were randomly used to separate the correct object from the foil object. After reaching a criterion before the operation, animals were given either hippocampal or cortical control lesions. In trials after the operation, control animals matched their performance before the operation across all spatial separations. In contrast, hippocampal-lesioned animals displayed impairments across all spatial separations with the exception of the longest (105 cm) spatial separation. The results suggest that the hippocampus may serve to separate incoming spatial information by temporarily storing one place separate from another. It is proposed that hippocampal lesions decrease efficiency in pattern separation, resulting in impairments in trials with increased spatial similarity among working-memory representations.

Animals↗
PubMed1998

Effects of hippocampal and parietal cortex lesions on the processing of multiple-object scenes.

Rats were taught 1 of 3 types of multiple-object scene discrimination. Manipulations included either replacing (object based), displacing (space based), or replacing and displacing (object/space based) 1 object in the scene. Once trained, rats received hippocampal, parietal cortex, or cortical control lesions and then were retested. Parietal cortex- and hippocampal-lesioned rats displayed deficits on both the space and object/space tasks but not the object task. The hippocampal-lesioned group's deficit on the object/space task was only transient, whereas the impairments of the parietal cortex-lesioned rats were stable for both tasks. The parietal cortex-lesioned rats sustained difficulty with the object/space task may indicate an inability to switch cognitive strategies.

Animals↗
PubMed1997

Short-term memory for food reward magnitude: the role of the prefrontal cortex.

Memory for magnitude of reinforcement was assessed in rats using a go/no-go short-term memory paradigm. During the task's study phase rats were given a piece of cereal comprised of either 25 or 50% sugar. For all trials, one of the cereal types was designated positive, the other negative. On the ensuing test phase the rat was presented with an object which covered a food well. If a positive food reward was given during the study phase, a second food reward was placed beneath the object. No food reward was placed under the object if the study phase consisted of a negative food reward. Latency to object displacement was used as the measure of performance. Following the establishment of a significant difference between latency to approach the object with reward compared to latency to approach the object without reward, rats were given either agranular insular cortex, anterior cingulate cortex, pre- and infralimbic cortex or control lesions. Agranular insular cortex lesioned animals demonstrated a mild post-surgery impairment. Trials consisting of 10 and 20 s delays between the study and test phases were then introduced. Delays exacerbated the previous deficit of the agranular insular cortex lesion group, but had little effect on the other lesion groups. All animals transferred to a new set of cereals containing 25 and 50% sugar and exhibited taste preferences to sugar solutions of different concentrations. These results indicate that the agranular insular cortex may play an important role in the processing of affect-laden information within a prefrontal cortex short-term or working memory system.

Animals↗
PubMed1988

Antibody producing ability of mouse spleen cells after subacute dietary exposure to T-2 toxin.

The effects of T-2 toxin on the antibody producing ability of CD-1 mice after dietary exposure to 0, 2.5, 5 and 15 ppm of T-2 toxin for 29 days was studied. The antibody response against sheep red blood cells, a T-lymphocyte and macrophage-dependent response was suppressed at 2.5, 5 and 15 ppm of T-2 toxin exposure. In contrast, the antibody responses against dinitrophenyl-aminoethylcarbamylmethyl - Ficoll (DNP - Ficoll), a T-lymphocyte independent macrophage-dependent response, and Escherichia coli 0127 (LPS), a T-lymphocyte and macrophage-independent response, were not affected. These results suggest that the inhibitory effects of T-2 toxin on antibody-producing ability after subacute dietary exposure appear to be a direct affect on T-lymphocyte function, possibly involving the T-helper lymphocytes.

Animals↗
PubMed1987

Immunological responsiveness of mouse spleen cells after in vivo or in vitro exposure to 3-acetyldeoxynivalenol.

The effects of 3-acetyldeoxynivalenol (3-AcDON) on mitogen-induced lymphocyte proliferation and antibody production were studied in male CD-1 mice exposed to 0, 2.5, 5 or 10 ppm 3-AcDON in the diet for 35 days. Mitogen-induced lymphocyte proliferation and T-cell-independent antibody responses to dinitrophenyl-ficoll or Escherichia coli were not altered by dietary exposure to 3-AcDON. The T-cell-dependent antibody response to sheep red blood cells was increased in the group fed 10 ppm 3-AcDON. In vitro, 3-AcDON inhibited lymphocyte proliferation in a dose-dependent manner. Inhibition was observed when the toxin was present during the first 8 hr in phytohaemagglutinin-stimulated cultures and during the first 24 hr in lipopolysaccharide-stimulated cultures. This suggests that 3-AcDON blocks an early step in lymphocyte activation. This inhibition was not restored by thiol reducing agents (dithiothreitol, L-cysteine or 2-mercaptoethanol). Similarly, the addition of lymphokines, including interleukin-1 or interleukin-2, did not alter the inhibitory effects of 3-AcDON. These results suggest that the in vitro effects of 3-AcDON may not reflect its in vivo immunotoxicity. However, 3-AcDON may serve as a chemical probe for examining the activation process of lymphocyte proliferation.

Animals↗
PubMed1986

In vitro effects of 3-acetyl-deoxynivalenol on the immune response of human peripheral blood lymphocytes.

The effects of 3-acetyl-deoxynivalenol (3-AcDON) on the in vitro mitogen responses and the antibody producing ability of human peripheral blood lymphocytes were evaluated. 3-AcDON inhibited the proliferative response to pokeweed mitogen and concanavalin A at a lower concentration (100 ng/ml) as compared to phytohemagglutinin (200 ng/ml). The antibody producing ability was inhibited by 3-AcDON concentrations of greater than or equal to 200 ng/ml. Higher concentrations of 3-AcDON (greater than or equal to 300 ng/ml) produced severe suppression of plaque forming cell response in vitro and reduced the total yield of lymphocytes without altering cell viability. The results of this study indicate that 3-AcDON produces immunosuppressive effects in a dose dependent manner in vitro.

Adult↗
PubMed1983

Alpha 1-antitrypsin phenotypes in Canadian Metis.

Alpha 1-antitrypsin phenotyping was performed on serum of 344 Metis living in an isolated northern Saskatchewan community. Only PiM and PiMZ phenotypes were observed with phenotype frequencies of 98.5 and 1.5 respectively. Gene frequencies were 0.993 for PiM and 0.007 for PiZ. The low frequency of non-M phenotypes is similar to that in another population of North American natives, the Eskimos of Igloolik as well as Finnish and Norwegian Lapps.

Canada↗
PubMed1980

Creatine kinase isoenzyme patterns in normal smooth muscle and smooth muscle neoplasms.

The CK isoenzyme composition of leiomyoma tissue is predominantly CK-BB and similar to adjacent myometrium tissue, while the leiomyosarcoma revealed a lesser quantity of CK-BB, but a greater quantity of CK-MM. The reasons for the discrepancy between the two types of neoplasms is not clear, but may reflect the changes which occur when smooth muscle becomes malignant.

Ankle↗
PubMed1980

Effect of actinomyces israelii on human peripheral lymphocytes.

Actinomycosis is rare and responds well to antibiotic therapy. The causative organism, Actinomyces israelii which is now considered to be a bacterium, has long been suspected of exerting an immunosuppressive effect. The authors provide further evidence of this in their study of three patients with actinomycosis and four healthy control subjects. Skin reactivity to various standard antigens was depressed in all seven patients. Peripheral lymphocytes from the patients and the control subjects were isolated. A. israelii was added to the cell cultures following challenge with several standard mitogens. Blast transformation in response to phytohemagglutinin was inhibited by A. israelii in all seven subjects, but was preserved in response to concanavalin A and pokeweed mitogen. A. israelii appears capable of inhibiting the subset of human peripheral lymphocytes responsive to phytohemagglutinin stimulation in vitro.

Actinomyces↗
PubMed1980

Creatine kinase isoenzyme patterns in neoplasms of peripheral nerve.

Normal peripheral nerve and neoplastic lesions of peripheral nerve varied in their creatine kinase (CK; EC 2.7.3.2) isoenzyme pattern, as assessed both with electrophoresis and with column chromatography. All three isoenzymes were seen in normal peripheral nerve, but the peripheral nerve tumors, neurofibroma and neurilemmoma, demonstrated predominantly CK-1 isoenzyme activity, with a trace amount of CK-3. No CK-2 activity was demonstrated in these tumors. In contrast, malignant schwannoma tissue contained all three isoenzymes, but in a different proportion than in normal peripheral nerve.

Creatine Kinase↗
PubMed1978

Ultrastructure of the skin of patients treated with sodium aurothiomalate.

Skin biopsies from cases of rheumatoid arthritis treated with sodium aurothiomalate were examined with the electron microscope. Intralysosomal gold deposits were found in the macrophages of both normal-looking skin and from areas of erythematous rash that had developed as a toxic manifestation of gold therapy. The main difference between affected and normal-looking skin was the presence of numerous mast cells in the former. It is hence suggested that the dermatologic side-effects of gold are probably mediated by the release of vasoactive substances from mast cells and that vigorous administration of antihistamines to neutralise the liberated products of mast cells or an agent that interferes with degranulation of mast cells might have a palliative effect on the skin rash that sometimes develops during chrysotherapy.

Adult↗
PubMed1975

Sjögren's syndrome terminating as a myeloproliferative disorder.

A 59 year old female was diagnosed as having Sjögren's syndrome in 1963. A short time later, she developed a refractory sideroblastic anemia. In 1972, she was found to have a preleukemic state with a persistent "shift to the left" of the granulocytic series, terminating early in 1974 as acute myeloblastic leukemia. Although several cases of malignant lymphomata have been described in association with Sjörgen's syndrome, to our knowledge no other example of Sjörgen's syndrome has been described in association with a myeloproliferative disorder. Defective immune surveillance produced by the Sjörgen's syndrome may have permitted the development of the myeloproliferative syndrome. Alternatively, both disorders may have developed from a hemopoietic stem cell defect.

Anemia, Sideroblastic↗
PubMed1974

Athyreotic cretinism associated with thymic hypoplasia and amyloidosis of lymphoid tissue.

A child presenting at 5 months of age with Hemophilus influenzae meningitis was also found to be severely hypothyroid. The child died two years later from the complications of measles pneumonia. At autopsy, no thyroid tissue was found and the thymus was hypoplastic. Most of the lymphoid tissues were infiltrated by amyloid.It is possible that there was a combined developmental defect involving thyroid and thymus. The alternatives are that the association occurred purely by chance or that the severe hypothyroid state led to thymic insufficiency.

Amyloidosis↗